Prediction of Pretreatment 18F-FDG-PET/CT Parameters on the Outcome of First-Line Therapy in Patients with Metastatic Breast Cancer.

Objective 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) can provide prognostic information, especially 18F-FDG uptake has been proven to be a predictor for the prognosis of various tumors. Nevertheless, the prognosis of other PET parameters in the metastatic setting remains unclear. This study was aimed at investigating pretreatment parameters based on 18F-FDG-PET/CT so as to estimate the progression-free survival (PFS) of metastatic breast cancer (MBC) patients receiving first-line treatment. Methods MBC patients who underwent a whole-body 18F-FDG-PET/CT prior to first-line therapy were enrolled. The heterogeneity parameter of PET/CT was analyzed, including heterogeneity index (HI) and general parameters (metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value (SUVmax) and mean SUV (SUVmean). PFS was used to evaluate the treatment outcome. Kaplan-Meier method was adopted to carry out survival analysis and Log rank test was conducted to make a comparison. Results A total of 177 MBC patients were selected, in which 68 were in De novo stage IV. Thirty patients were human epidermal growth factor receptor 2 (HER2)-positive, 60 patients were triple-negative, and 87 patients were hormone receptor (HR)-positive and HER2-negative. In the whole population, patients with high baseline SUVmax, SUVmean, MTV, TLG or HI were associated with lower PFS (P=0.028, 0.005, 0.017, 0.026 and 0.035, respectively). Among the patients in De novo stage IV, those with high HI at baseline had significantly shorter PFS (P=0.001). In HR+/HER2- and HER2+ subgroups, only baseline HI showed the predictive value of PFS (P=0.023 and 0.049, respectively). In the triple-negative subgroup, high baseline SUVmax, MTV or TLG showed the predictive value of worse PFS (P=0.030, 0.011 and 0.023, respectively). Conclusion Pretreatment 18F-FDG-PET/CT parameters show the predictive value of PFS in MBC patients receiving first-line treatment. However, predictive PET/CT parameters might be different in patients with different molecular subtypes and De novo stage IV.